I have read that the nlock time function would allow me to spend coins now which would then be included in a block at a set date in the future. For example, I want to set aside some coins for my son/daughter for when they become an adult but I want to ensure in the meantime, the same coins cannot be accessed by either myself, the child or anyone else up until that time. How would I go about using nlock and securing a wallet for access in approx 15-20 years time? Would I be correct to assume that even if QT client isn't around then and the wallet.dat file is lost, provided they have the private key for the public address, they should be able to import the key into whatever client is used in 15-20 years time?
Also - would such a date and time be public knowledge on the blockchain? I'm debating whether it would be wiser sending the coins to a wallet that is encrypted yet available now to anyone that has access to the password on paper or locking these coins up for a set date so that no-one can access them until such time.
Yes, you only need the private key to spend the coins related to this.
But I do not understand how nlock works.
I do not think that it is possible to "lock" coins for an amount of time.